A repeater has been used to achieve objects such as improving quality of broadcasting services, satisfying broadcasting standards, and extending a radio wave radius when repeating a radio wave of a high frequency band.
Further, in the case of shadow regions such as a tunnel, with an underground roadway radio where a radio wave of a transferred signal is weak, the repeater has been used to amplify the weak signal.
The repeater is subdivided into a varied wave type, a non-varied wave type, an optical type, a microwave type, and the like. In the case of the non-varied wave type of repeater, it can amplify and transceive the co-channel signal while reducing the magnitude as a whole, such that an available range of a frequency band can be extended and a waste of installation space can be prevented. As a result, the non-varied wave type of repeater has widely been used in radio communication.
However, in the non-varied wave type of repeater in the related art, since an antenna for receiving a signal and an antenna for transmitting a signal are provided in a single body as shown in FIG. 1, it has a problem in causing oscillation due to signals that are transmitted from the transmitting antenna and then fed back to the receiving antenna, that is, feedback signal.
The oscillation degrades performance of devices, causes a failure, and increases maintenance costs. Moreover, since the oscillation degrades the quality of repeated signals, when the non-varied wave type of repeater is applied to broadcast repeating that should simultaneously transfer voice and video signals, they become main factors of degrading the repeating performance.
In order to solve the above problems, the non-varied wave type of repeater in the related art has adopted a type where a unit that is capable of cancelling the feedback signal is provided.
However, most cancelling units are configured as a type that discriminates a signal to be received through the receiving antenna, that is, an original signal to be repeated, and removes feedback signal and then compares the magnitude thereof to cancel a signal having a small magnitude.
Therefore, the feedback signal cancelling unit of the non-varied wave type of repeater in the related art of the above-mentioned type has a limitation in improving the repeating performance only within the range of satisfying the precondition where the magnitude of the feedback signal should be smaller than that of the original signal.
Thereby, in the related art, the non-varied wave repeater as well as a varied wave type repeater was used.
However, the varied wave type repeater, which adopts a scheme that simply makes frequencies of input and output signals different to prevent the feedback signal from being received, has a problem in that it should extend the range of the frequency band required for the system as a whole.
In other words, the varied wave type of repeater does not solve fundamental problems in that it is difficult to improve operating efficiency and to reduce costs consumed for installation or maintenance
In particular, in the case of the non-varied wave repeater and the varied wave repeater in the related art, the regeneration of the repeated signals cannot be expected since they simply amplify and repeat the signals received from the transmitter.
Therefore, they have problems in that they are not suitable for repeating the broadcasting signals that require a high quality of broadcasting standards.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.